1. Field of the Invention
The present invention relates to a processing system for performing a plurality of processes for a target substrate, e.g., a semiconductor wafer and, more particularly, to a system for applying a process liquid, e.g., a photoresist.
2. Description of the Related Art
A photoresist coating system is employed in a semiconductor device manufacturing process. As indicated in U.S. Pat. No. 5,061,144, this system usually comprises an adhesion process chamber, a pre-bake chamber, a cooling chamber, and a resist coating chamber. In the adhesion process chamber, in order to improve the adhesion properties between a semiconductor wafer as a target substrate and a resist film, the wafer surface is subjected to a hydrophobic process. In the pre-bake chamber, the solvent remaining in the resist coated on the wafer is heated to evaporate. In the cooling chamber, the wafer heated in the pre-bake chamber is cooled. In the resist coating chamber, a resist solution is coated, by rotation, on the surface of the wafer which is cooled to a predetermined temperature in the cooling chamber.
These process chambers are arranged along a wafer convey path, and loading and unloading of the wafers to and from the respective process chambers are performed by a convey robot that moves on the wafer convey path. The convey robot has a travel block that travels on the convey path, and a handling arm supported on the travel block.
Another convey robot is also developed which has a pair of upper and lower handling arms supported by a travel block and driven independently of each other. In this case, one arm is used for taking out a wafer, and the other arm is used for inserting a wafer, so that wafers can be efficiently transferred.
In this system, the thickness and quality of the resist film sometimes vary depending on the processing states. In a resist coating and developing system additionally having a developing chamber, the developing speed sometimes varies depending on the processing states. These variations in thickness and quality of the resist films and in developing speed decrease the yield of semiconductor devices as products.